Dengue virus (DV) is a mosquito-borne pathogen that causes dengue fever (DF) and severe life threatening illness, dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). DV is a small, enveloped, positive-stranded RNA virus that belongs to the Flavivirus genus of the Flaviviridae family which also includes Zika virus, and yellow fever virus. Four distinct subtypes or serotypes of dengue viruses (DV-1 to DV-4) are transmitted to humans through the bites of mosquito species Aedes aegypti and Aedes albopictus. It has been estimated that 50-100 million cases of DF and 250,000-500000 cases of DHF occur every year. Dengue constitutes a significant international public health concern, as two-fifths of the world's population live in dengue endemic regions, and an estimated 50-100 million cases of dengue infection occur annually. Furthermore 2.5 billion people are at risk for infection in subtropical and tropical regions of the world in the absence of effective intervention.
There are four dengue virus subtypes: dengue-1 (DV1), dengue-2 (DV2), dengue-3 (DV3), and dengue-4 (DV4). Each one of these subtypes form an antigenically distinct subgroup within the Flavivirus family. Despite extensive cross-reactivity among these viruses in serological tests, there is no cross-protective immunity in humans. Individuals living in an endemic area can have as many as four infections, one with each serotype, during their lifetimes.
DV encodes a nonstructural glycoprotein, NS1 (FIG. 16), which associates with intracellular membranes and the cell surface. NS1 is eventually secreted as a soluble hexamer from DV-infected cells and circulates in the bloodstream of infected patients. Therefore, NS1 serves as a convenient target antigen for detecting and diagnosing infection of a human patient potentially infected with one or more serotypes of dengue virus by providing a blood sample from such patient for testing.
While it is desirable to be able to detect all four dengue serotypes, implementation of a single assay that is highly sensitive for all serotypes has been hampered by limited relatedness of the viral targets at the nucleic acid level. Therefore, there remains a need to develop an accurate diagnostic that can detect and distinguish between all four dengue virus serotypes.